This invention relates generally to off-road motor vehicles, such as tractors, and more particularly, to an interlock mechanism cooperable with a creeper gear to control engagement thereof under specified conditions.
Contemporary tractor transmissions have become mechanically complicated, incorporating sixteen or more forward speeds and usually half as many speeds in reverse, along with hydraulic, electric or electronically controlled shifting mechanisms to change the selected speed of operation of the tractor. The various operations for which tractors are employed require such a wide range of options and speeds of operation. Some specialized harvesting operations, among others, require very slow speeds of operation, which are typically provided through a "creeper gear" or range of gears.
Creeper options for tractors introduce design challenges. When in "creeper gear", the tractor is usually capable of a very slow speed of movement over the ground with the ability to pull with several thousands of pounds of force. In some tractor transmissions, internal drag between the gears and the oil bath for the gears can transmit this pulling force from the engine to the output shaft of the transmission even though the transmission gears are not engaged, i.e. the transmission is in neutral, resulting in unwanted creep of the tractor.
It is desirable to provide a tractor transmission having a crooper gear arrangement in which the unwanted creep, occurring when the transmission is in a neutral state through drag within the transmission, is prevented by an interlock mechanism associated with the tractor engine.